The traditional Japanese method for the preparation of a nutritional, non-alcoholic beverage from rice requires the blending of steamed or cooked rice with rice koji. The rice koji is prepared by inocculating steamed or cooked rice with the spores of the mold (Aspergillus oryzae) and cultivating the inocculated rice.
The rice koji contains a significant conglomeration of enzymes, predominantly alpha-amylase. It is characterized by both dextrinizing or liquefying and saccharifying action on starch.
After cultivation or fermentation for periods between 4 and 48 hours, the saccharified mass is passed through a sieve or filter. Dependent upon the starting materials used, (polished or unpolished rice or combination thereof) the filtrate is a white to beige colored slurry having a distinctly sweet, rice-like taste. The texture and sweetness of the slurry is determined by the total solids and the degree of starch conversion and may be mildly sweet or thick and sweet (similar to a milk-shake). This nutritional beverage prepared from rice is commonly termed amazake.
The amount of sweetness derived from the amazake is dependent upon the total solids of the liquid and the amount of time the rice is allowed to culture with the koji under optimum conditions. Sweet amazake products resulting from long culturing times have an inherent problem of developing a "flat" or "sour" flavor. This flat souring presumably is the result of microbial action in the nutrient rich media as well as the oxidation of fats naturally occurring in the rice.
In some cases, culturing is terminated prior to the development of this flat souring. However, this results in the limitation of the amount of conversion from rice starch to maltose, glucose and higher dextrins. Typically, amazake prepared using koji results in the relative formation of substantial quantities of maltose and very low levels of glucose typically no more than two to three percent of the total carbohydrates. This quantitative relationship between maltose and glucose is limited by the nature of the koji culture itself. lt is these limitations on the quality and quantity of sugars produced in making amazake via the traditional koji method that prompted us to seek an alternative.
The use of enzymes as an alternative method for the liquefaction and saccharification of starch from grains and tubers other than rice is very well known for the production of 100% carbohydrate products including dextrins, fillers and sweeteners intended to be competitive with sucrose. In these products, usually made from corn, the starch-containing portion of the grain or tuber is first separated from the non-starch containing portions before enzymatic conversion. Thus, a relatively pure starch is obtained which can be enzymatically converted and processed to produce a pure carbohydrate product free of impurities.
Because of the preliminary separation of the starch fragment from the grain, not only is a pure carbohydrate product obtained but the enzymatic conversion process is uncomplicated and uninhibited by the fat, fiber and protein contaminants. Unfortunately, this enzymatic conversion process yields a relatively pure carbohydrate product and therefore does not have the nutritional advantages yielded by the traditional koji method involving whole or ground rice.
Traditionally prepared amazake using koji produces a thick, pulpy type of beverage with a rice-like flavor, limited sweetness and stability, and in most cases a distinct sour flavor. Because of its textural and functional properties, this traditionally prepared amazake has a very limited usage, if any, as a substitute for milk.
Accordingly, there has been found to remain a need for improved rice liquids which can be employed either as a beverage or in the preparation of food products. Because of the generally non-allergenic response to rice, it may be anticipated that such products may have a similar characteristic oi being generally non-allergenic.
As an example of other beverage products developed for this market, soy beverages have been employed recently as a milk substitute in powdered, canned and aseptic packaged form. Disadvantages associated with these soy-based milk substitutes arise primarily because of the allergenic response which many people have toward soy products, the bean-like flavor of the products and their common need for the addition of a sweetener.
As noted above, there has been found to remain a need for an improved rice liquid product and method of its preparation.
Another invention set forth in a copending application, Ser. No. 06/856,504 filed Apr. 28, 1986, entitled RICE SYRUP SWEETENER AND METHOD OF PRODUCTION, and assigned to California Natural Products is related to the present invention and is accordingly incorporated herein by reference as though set forth in its entirety. The above noted reference involves rice syrup sweeteners which are formed by generally the same steps employed for the nutritional rice milk product of the present invention. However, as a final step, the rice syrup sweeteners are partially clarified, preferably by sieving and centrifuging in order to remove substantially all rice fiber from the product resulting in the rice syrup sweetener. That reference is incorporated herein to the extent that it may be of assistance in disclosing and facilitating a further understanding of the present invention.